Mesh seems to still be proportionally editing even though it is turned off
You have the Subsurf modifier on your object, that is why your model appears so smooth and you have set it to show the cage or its active effect while editing. The modifier might have been accidentally added as the shortcut is simply Ctrl 0 - 5 for each smoothing level (higher number being more subdivisions). If you want to disable this, delete it from the object or if you want to stop the "proportional editing effect", untick the triangle icon on the modifier.



When doing organic modeling, having the cage on is often useful to see the changes in realtime when tweaking loops or filling faces as opposed to tabbing in and out of edit mode and object mode to the the updates.

Since you have the cage enabled, it will show how the subsurf modifier is deforming the mesh as you work with it, if you are in the early stages of modeling and inexperienced, it's probably a good idea to keep this off until you have the general shape of your model in place and work with the flat "boxy" mesh. Reason being the modifier can produce exaggerated results that differ from when you look at the smoothed and unsmoothed model. The subsurf modifier will effectively "shrink/round" the mesh as it tries to create smoothed surfaces.

To see what I mean, add a cube and press Ctrl1 to add a subsurf modifier with 1 subdivison level. Play with the object with the cage on and then disable the modifier to see how it has changed the underlying structure of your object.